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Biomedical subjects

W Thompson

Publications and source records attributed to W Thompson.

At least 163 records · Page 9Linked to original sources
PubMed1975

Different selectivities in acylation and methylation pathways of phosphatidylcholine formation in guinea pig and rat livers.

Radioactivity from intraperitoneally or intraportally injected 1-acyl-snglycero-3-phosphorylcholine, doubly labelled in either palmitoyl, glycerol or phosphoryl moities, was incorporated largely into disaturated or mixed disaturated-oligoenoic fractions of phosphatidylcholine in guinea pig liver. In rat liver the tetraenoic class was the most highly labelled and only very low radioactivity was recovered from disaturated or monoenoic species. The methylation of phosphatidylethanolamine to phosphatidylcholine, as judged by the incorporation of intraperitoneally injected L-[Me-14 C] methionine, involved selectively tetraenoic and polyenoic (greater than 4 double bonds) classes in rat liver. In guinea pig liver, methylation activity was much lower and led to the formation principally of dienoic classes of phosphatidylcholine. These experiments confirm the work of others that in rat liver, which has a high level of polyunsaturated classes of phosphatidylcholine, the "indirect" pathways of synthesis give rise chiefly to these classes. However, the priorties in guinea pig liver are different, since the levels of polyunsaturated classes are much lower, and although the "indirect" pathways of synthesis are operative they are directed mainly toward the formation of more saturated classes.

Acylation↗
PubMed1975

Isolation and characterization of cytidine diphosphate diglyceride from beef liver.

Cytidine diphosphate diglyceride was isolated from beef liver by a combination of silicic acid column, DEAE-cellulose column, and this layer chromatography. The product (5.8 to 17.4 mumol/kg of liver) contained cytidine/phosphate/fatty acids in the molar proportions 1.05/2.0/2.05 (theoretical, 1.0/2.0/2.0) (average for three preparations). The liponucleotide was split quantitatively by a partially purified hydrolase from Escherichia coli, specific for CDP-diglyceride, (Raetz, C. R. H., Hirschberg, C. B., Dowhan, W., Wickner, W. T., and Kennedy, E. P. (1972) J. Biol. Chem. 247, 2245-2247) into phosphatidic acid and a water-soluble nucleotide that was chromatographically identical with CMP. No dCMP was located in these hydrolysates. The liver liponucleotide was more effective than a synthetic preparation of CDP-diglyceride in promoting the formation of phosphatidylinositol with guinea pig brain microsomes. The fatty acid composition of CDP-diglyceride was compared with metabolically related phospholipids from beef liver. The liponucleotide had a similar composition to phosphatidylinositol, characterized by a high level of stearate and with arachidonate as the major unsaturated fatty acid. The content of arachidonate in both lipids was significantly higher than that in phosphatidic acid. The profile of fatty acids of cardiolipin was quite unlike that of CDP-diglyceride. These findings suggest several alternatives for the metabolic origins of beef liver CDP-diglyceride: (a) CDP-diglyceride is formed from an atypical pool of phosphatidic acid, (b) the enzyme is selective for arachidonoyl-containing species of phosphatidic acid, (c) the liponucleotide may also be derived from phosphatidylinositol by the back-reaction of CDP-diglyceride: inositol phosphatidyltransferase.

Animals↗
PubMed1975

Transfer of phosphatidylserine from liposomes or microsomes to mitochondria. Stimulation by a cell supernatant factor.

Incubation of microsomes or sonicated dispersions of microsomal lipid containing (14-C)phosphatidylserine with rat liver mitochondria results in the transfer of radioactivity to the mitochondria. Transfer is time and temperature dependent and is stimulated by a factor in the 105 000 x g supernatant from liver homogenates. The supernatant factor is soluble at pH 5.1, stable to dialysis, and is inactivated by heating and by digestion with trypsin. Radioactivity accumulates in the mitochondria largley as phosphatidylethanolamine owing the activity of phosphatidylserine decarboxylase. Transfer to mitochondria, heat treated to inactivate the decarbosylase, is also promoted by the suppernatant factor, in which case the lipid appears to be incorporated into the mitochondrial membrane as unchanged phosphatidylserine.

Animals↗
PubMed1975

Selective planned induction in conditions of civil strife.

Selective planned induction may be defined as the initiation of labour by artificial means for reasons not strictly medical. Where the indications are merely social or for conveniencewhether patient's, hospital's, or doctor'sīt is doubtful that the procedure is acceptable until we have more detailed knowledge of its effects on the mother and fetus. However, the civil strife that occurred in Belfast in 1972 provided conditions in which the present study of the technique seemed justified. The results suggest that, provided the selection criteria are sufficiently rigorous and meticulously applied, there are no serious maternal risks. The main fetal risk is of unexpected prematurity; this can be avoided, but the precautions applied in this preliminary study reduced significantly the number of patients for whom the method could be used. A second series, with controls and using less rigorous selection criteria, is at present being studied.

Apgar Score↗
PubMed1975

Phosphatidylethanolamine in liver mitochondria and endoplasmic reticulum: molecular species distribution and turnover.

Phosphatidylethanolamine from mitochondria and microsomes of guinea pig liver was separated by thin-layer chromatography into eight different classes differing in degree of unsaturation. The fatty acid compositions and molar proportions of each class isolated from microsomes were very similar to the corresponding class in mitochondria. In both organelles about half of the total was dienoic species while tetraenes comprised approximately 20%. Stearic acid was the major saturated fatty acid and in each membrane a greater selectivity for stearate over palmitate was found in each sub-class of phosphatidylcholine. Following the intraperitoneal injection of [2 minus-3 H]glycerol, the labelling of each molecular class of phosphatidylethanolamine showed very similar progressions in microsomes and mitochondria over a 3 h interval. In both organelles the highest relative specific activity was attained by penta-plus hexaenoic classes, while the large dienoic class had the lowest relative activity, which, however, increased with time. Analysis of the dienoic class of phosphatidyl-ethanolamine from whole liver showed it to be constituted by a rapidly turning over palmitoyl-linoleoyl fraction and a slowly labelled stearoyl-linoleoyl fraction, a pattern also exhibited by dienoic phosphatidylcholines. The similarities in profile of molecular classes of phosphatidylethanolamine and in the kinetics of labelling in vivo point to a close metabolic relation between the lipids of both organelles, suggestive of a transfer of different molecular classes at comparable rates from the endoplasmic reticulum, the site of synthesis, to the mitochondria. This is consistent with numerous other studies in vitro that have demonstrated inter-organelle exchange of lipids.

Animals↗
PubMed1975

A comparison of the physical and intellectual development of black children with and without sickle-cell trait.

Sickle-cell trait, a condition present in 7% to 9% of the United States Black population, is usually considered to be a clinically benign condition. However, there is increasing evidence to indicate the contrary, that is, the clinical pathophysiology is variable, ranging from a benign condition in most cases to a relatively few cases of severe pathological involvement. Physical and intellectual growth measures were taken on 19 children with sickle-cell trait (12 boys and 7 girls) from a large study of Black same-sex twin pairs from Philadelphia, Pennsylvania, and compared to measures taken of a sample of normal Black children from 155 monozygotic and dizygotic same-sex twin pairs. Sickle-cell trait carriers were found to weigh less, have smaller upper arm circumference lesser skinfold thickness, and showed less mature skeletal age, differing significantly from normal children. Sickle-cell carriers tended to score lower on four of five intellectual measures, scoring one fifth to one third of a standard deviation lower than normal children.

Adolescent↗